In general, in the case of a plug-in hybrid electric vehicle (PHEV) that travels by using energy output from a battery as a power source, it is necessary to charge an internal battery by driving a vehicle motor and in this case, an element called a relay is used to apply current which flows between a charge source and a battery or block the current between the charge source and the battery.
Moreover, when various elements need to be protected in a situation in which overcurrent which is more than a threshold flows on an internal circuit of the electric vehicle, a state of the relay is changed from an on state to an off state, and as a result, the current on the circuit is blocked to protect various elements.
Meanwhile, in the electric vehicle, the relay in the related art is controlled by a micro controller unit (MCU) and the micro controller unit allows a constant current to flow on a relay coil to generate magnetic force and a moving core contacts both contacts between the circuits by the generated magnetic force to maintain the current to be applied between the circuits.
However, as the magnetic force generated from the relay coil is diffused to the outside, there is a problem in that electro magnetic interference (EMI) occurs.
Further, since the constant current needs to flow on the relay coil in order for the moving core to maintain the contact both contacts between the circuits, there is a problem in that a power consumption rate of the relay in the related art is high.
Moreover, in the relay in the related art, when an error occurs in a pattern on the circuit between a high side driver or the micro controller unit and the relay, even though the overcurrent which is more than a threshold flows, a circuit for independently controlling the relay is not configured, and as a result, there is a problem in that the relay cannot be controlled.
Accordingly, in order to solve the problems of the relay in the related art, the present inventor has invented a system and a method for independently controlling the relay using bimetal which allow the bimetal to operate based on a signal output from the micro controller unit when the current of the predetermined threshold or more flows on the circuit to allow current which flows between the battery and the relay to flow bypassing the bimetal to independently control the relay regardless of whether the circuit pattern is abnormal.